Electrochemical water softening system

ABSTRACT

Systems and methods for treating water are provided. The systems and methods may utilize an electrochemical water treatment device comprising ion exchange membranes. In certain systems and methods, a concentrate stream and a dilution stream may be in fluid communication with ion exchange membranes. The ion exchange membranes may be configured to provide a ratio of a pH of the concentrate stream and a pH of the dilution stream to be less than about 1.0. In some instances, the LSI of the concentrate stream may be less than or about 1.0. In certain instances, the electrochemical water treatment device does not require a reverse polarity cycle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit under 35U.S.C. §120 of co-pending U.S. patent application Ser. No. 14/772,269titled ELECTROCHEMICAL WATER SOFTENING SYSTEM filed on Sep. 2, 2015,which is a U.S. National Phase Application under 35 U.S.C. §371 ofInternational Application No. PCT/US2014/024220, filed Mar. 12, 2014,titled ELECTROCHEMICAL WATER SOFTENING SYSTEM, which claims priorityunder 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/798,756,filed Mar. 15, 2013, titled ELECTROCHEMICAL WATER SOFTENING SYSTEM, eachof which is incorporated by reference herein in its entirety for allpurposes.

FIELD OF THE DISCLOSURE

Aspects generally relate to a system and method for treating water froma point of entry by contacting a source of feed water with at least oneion exchange membrane housed in an electrochemical water treatmentdevice to produce water suitable for residential or commercialapplications.

SUMMARY

In accordance with one or more embodiments, a water treatment system fora residential or commercial application is provided. The water treatmentsystem comprises an electrochemical water treatment device comprising atleast one ion exchange membrane, a concentrate stream in fluidcommunication with the at least one ion exchange membrane, and adilution stream in fluid communication with the at least one ionexchange membrane, wherein the at least one ion exchange membrane isconfigured to provide a ratio of a pH of the concentrate stream and a pHof the dilution stream to be less than about 1.0. According to at leastone embodiment, the ratio of the pH of the concentrate stream and the pHof the dilution stream is about 0.9. In some embodiments, the pH of theconcentrate stream is less than or about 7.0. In certain aspects, an LSIof the concentrate stream is less than or about 1.0. In a furtheraspect, the LSI of the concentrate stream is less than or about 0.5. Inat least one aspect, a conductivity, an alkalinity, and a pH of thedilution stream are about 300 μS/cm, about 100 ppm, and greater thanabout 7.0, respectively. In a further aspect, an LSI of the concentratestream is about 0.2. In another aspect, the system does not require aseparate source of acidic water for the concentrate stream. In someaspects, the system does not require a reverse polarity cycle. Accordingto at least one embodiment, the at least one at least one ion exchangemembrane is configured to require at least about 25% less time to reducea hardness of a feed stream to a predetermined level than anelectrochemical device that does not comprise the at least one ionexchange membrane.

In accordance with one or more embodiments, a method of treating waterfor a residential or commercial application is provided. The methodcomprises feeding water from a point of entry to an electrochemicalwater treatment device and passing the feed water through aconcentrating compartment and a diluting compartment of theelectrochemical water treatment device to produce a concentrate streamand a product stream. A ratio of a pH of the concentrate stream to a pHof the product stream is less than about 1.0. In at least one furtheraspect, the ratio of the pH of the concentrate stream to the pH of theproduct stream is about 0.9. According to some embodiments, the methodfurther comprises recirculating the concentrate stream. In variousembodiments, the pH of the recirculating concentrate stream is less thanor about 7.0. In at least one embodiment, the method further comprisescalculating an LSI of the concentrate stream. In various aspects, theLSI of the concentrates stream is less than or about 1.0. In variousaspects, an LSI of the concentrate stream is less than about 1.0. Invarious further aspects, the LSI of the concentrate stream is less thanor about 0.5. According to some embodiments, the method furthercomprises storing at least a portion of the product stream and measuringa conductivity, an alkalinity, and a pH of the stored portion of theproduct stream. In various embodiments, the conductivity, thealkalinity, and the pH of the stored portion of the product stream areabout 300 μS/cm, about 100 ppm, and greater than about 7.0,respectively. In a further embodiment, the method further comprisescalculating an LSI of the concentrate stream. In some embodiments, theLSI of the concentrate stream is about 0.2. In some aspects, the methoddoes not require the addition of a separate source of acidic water tothe concentrate stream. In certain aspects, the method does not requirea reverse polarity cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the systems and methods described hereinwill be described by way of example, and optionally, with reference tothe accompanying drawings. In the following description, variousembodiments of the systems and methods described herein are describedwith reference to the following drawings, in which:

FIG. 1 is a schematic illustration of an electrochemical water treatmentdevice in accordance with one or more embodiments;

FIG. 2 is a process flow diagram of a water treatment system inaccordance with one or more embodiments;

FIG. 3 is a process flow diagram of a water treatment system inaccordance with one or more embodiments; and

FIG. 4 is a chart illustrating at least one result from a comparisonstudy performed in accordance with one or more embodiments.

DETAILED DESCRIPTION

Water that contains hardness species such as calcium and magnesium maybe undesirable for some uses, for example, in industrial, commercial,residential, or household applications. Hard water requires more soapand synthetic detergents for home laundry and washing, and contributesto scaling in pipes, boilers and industrial equipment. Hardness iscaused by compounds of calcium and magnesium, as well as a variety ofother metals, and is primarily a function of the geology of the areawhere the ground water is located. Water acts as an excellent solventand readily dissolves minerals it comes in contact with. As water movesthrough soil and rock, it dissolves very small amounts of minerals andholds them in solution. Calcium and magnesium dissolved in water are thetwo most common minerals that make water “hard,” although iron,strontium, and manganese may also contribute. The hardness of water isreferred to by three types of measurements: grains per gallon (gpg),milligrams per liter (mg/L), or parts per million (ppm). Hardness isusually reported as an equivalent quantity of calcium carbonate (CaCO₃).One grain of hardness equals 17.1 mg/L or 17.1 ppm of hardness. Thetypical guidelines for a classification of water hardness are: zero to60 mg/L of calcium carbonate is classified as soft; 61 mg/L to 120 mg/Las moderately hard; 121 mg/L to 180 mg/L as hard; and more than 180 mg/Las very hard.

Alkalinity and hardness are both important components of water quality.Alkalinity is a measure of the amount of acid (hydrogen ion) water canabsorb (buffer) before achieving a designated pH. Total alkalinityindicates the quantity of base present in water, for example,bicarbonates, carbonates, phosphates, and hydroxides. Hardnessrepresents the overall concentration of divalent salts for example,calcium, magnesium, and iron, but does not identify which of theseelements is/are the source of hardness.

Hard water contains greater than about 60 ppm of calcium carbonate andis often treated prior to use by being passed through a water softener.Typically, the water softener is of the rechargeable ion exchange typeand is charged with cation resin in the sodium form and anion resin inthe chloride form. As water passes through the resin bed, majorcontributors to hardness, such as calcium and magnesium species, areexchanged for sodium. In this manner, the water can be softened by awater softening system as the concentration of divalent cations and, inparticular, calcium and magnesium ions decrease.

Ion exchange is the reversible interchange of ions between a solid (forexample, an ion exchange resin) and a liquid (for example, water). Sinceion exchange resins act as “chemical sponges,” they are ideally suitedfor effective removal of contaminants from water and other liquids. Ionexchange technology is often used in water demineralization andsoftening, wastewater recycling, and other water treatment processes.Ion exchange resins are also used in a variety of specializedapplications, for example, chemical processing, pharmaceuticals, mining,and food and beverage processing.

In water softening systems, the hardness ions become ionically bound tooppositely charged ionic species that are mixed on the surface of theion exchange resin. The ion exchange resin eventually becomes saturatedwith ionically bound hardness ion species and must be regenerated.Regeneration involves replacing the bound hardness species with moresoluble ionic species, such as sodium chloride. The hardness speciesbound on the ion exchange resin are replaced by the sodium ions and theion exchange resins are ready again for a subsequent water-softeningstep. However, an equivalent of sodium is added to the treated water forevery equivalent of calcium that is removed. Thus, although the water issoftened, the hardness is replaced with sodium ions that some consumersmay find undesirable. Furthermore, when these ion exchange beds arerecharged, the resulting brine must be disposed of and is oftendischarged to a septic system where the brine becomes available tore-enter the ground water. In certain regions, discharge of brine to adomestic septic system or to the environment is regulated or prohibited.

Other methods of softening water include the use of reverse osmosisdevices that can supply high purity water, but generally do so at a slowrate and require the use of a high pressure pump. Furthermore, manyreverse osmosis membranes can be fouled by the presence of dissolvedmaterials such as silica, which may often be found in well water.

Quality drinking water is often associated with highly purified water.However, as long as the water is free of microbial contamination, thebest drinking water may not necessarily be the most chemically pure. Forexample, water that has been purified to a high resistivity, forexample, greater than about 1 megaOhm, may be so devoid of ionic contentthat it becomes “hungry” and corrosive to material, such as copper, thatmay be used in water piping systems. Taste may also be affected by, forinstance, the removal of bicarbonate species. Furthermore, beneficial ordesirable chemicals that have been added to the water, for example,fluoride and chlorine species, may be removed along with undesirablespecies, resulting in water that may need to be re-fortified. In someregions, minimum levels of calcium may be necessary in order to complywith health and safety regulations and a high purity system that removesgreater than, for example, 90% or 99% of the calcium from the watersupply may be inappropriate.

Devices for purifying fluids using electrical fields are commonly usedto treat water and other liquids containing dissolved ionic species.Within these devices are concentrating and diluting (or depletion)compartments separated by ion-selective membranes. An example of such adevice is shown in FIG. 1, and includes an electrochemical watertreatment apparatus featuring alternating electroactive semipermeableanion and cation exchange membranes. Spaces between the membranes areconfigured to create liquid flow compartments with inlets and outlets.An applied electric field imposed via electrodes causes dissolved ions,attracted to their respective counter-electrodes, to migrate through theanion and cation exchange membranes. This generally results in theliquid of the diluting compartment being depleted of ions, and theliquid in the concentrating compartment being enriched with thetransferred ions.

As used herein, the phrases “treatment device” or “purification device”or “apparatus” pertain to any device that can be used to remove orreduce the concentration level of any undesirable species from a fluidto be treated. Examples of suitable treatment apparatuses include, butare not limited to, ion-exchange resin devices, reverse osmosis,electrodeionization, electrodialysis, ultrafiltration, microfiltration,and capacitive deionization devices.

In certain non-limiting embodiments, the methods and systems disclosedhere comprise an electrochemical water treatment device. As used herein,the phrase “electrochemical water treatment device” refers to any numberof electrochemical water treatment devices, non-limiting examplesincluding, but not limited to, electrodeionization devices,electrodialysis devices, capacitive deionization devices, and anycombination thereof. The electrochemical water treatment devices mayinclude any device that functions in accordance with the principles ofthe systems and methods described herein as long as they are notinconsistent or contrary these operations.

In certain embodiments, the electrochemical treatment device may includeelectrochemical deionization units. Non-limiting examples of suchdevices include electrodialysis (ED), electrodialysis reversal (EDR),electrodeionization (EDI), capacitive deionization, continuouselectrodeionization (CEDI), and reversible continuouselectrodeionization (RCEDI).

Electrodeionization (EDI) is a process that removes, or at leastreduces, one or more ionized or ionizable species from water usingelectrically active media and an electric potential to influence iontransport. The electrically active media typically serves to alternatelycollect and discharge ionic and/or ionizable species and, in some cases,to facilitate the transport of ions, which may be continuously, by ionicor electronic substitution mechanisms. EDI devices can compriseelectrochemically active media of permanent or temporary charge, and maybe operated batch-wise, intermittently, continuously, and/or even inreversing polarity modes. EDI devices may be operated to promote one ormore electrochemical reactions specifically designed to achieve orenhance performance. Further, such electrochemical devices may compriseelectrically active membranes, such as semi-permeable or selectivelypermeable ion exchange or bipolar membranes. Continuouselectrodeionization (CEDI) devices are EDI devices known to thoseskilled in the art that operate in a manner in which water purificationcan proceed continuously, while ion exchange material is continuouslyrecharged. CEDI techniques can include processes such as continuousdeionization, filled cell electrodialysis, or electrodiaresis. Undercontrolled voltage and salinity conditions, in CEDI systems, watermolecules can be split to generate hydrogen or hydronium ions or speciesand hydroxide or hydroxyl ions or species that can regenerate ionexchange media in the device and thus facilitate the release of thetrapped species therefrom. In this manner, a water stream to be treatedcan be continuously purified without requiring chemical recharging ofion exchange resin.

Electrodialysis (ED) devices operate on a similar principle as CEDI,except that ED devices typically do not contain electroactive mediabetween the membranes. Because of the lack of electroactive media, theoperation of ED may be hindered by feed waters of low salinity becauseof elevated electrical resistance. Also, because the operation of ED onhigh salinity feed waters can result in elevated electrical currentconsumption, ED apparatuses have heretofore been most effectively usedon source waters of intermediate salinity. In ED based systems, becausethere is no electroactive media, splitting water is inefficient andoperating in such a regime is generally avoided.

A capacitive deionization (CapDI) device is used to remove an ionicmaterial from a medium, for example, hard water, by applying a voltageto a pair of electrodes having nanometer-sized pores to polarize thepair of electrodes. This allows ionic material to be adsorbed onto asurface of at least one of the pair of electrodes. In the CapDI device,a low DC voltage is applied to the pair of electrodes and the mediumcontaining dissolved ions then flows between the two electrodes. Anionsdissolved in the medium are adsorbed and concentrated in the positiveelectrode, and cations dissolved in the medium are adsorbed andconcentrated in the negative electrode. When a current is supplied in areverse direction, for example, by electrically shorting the twoelectrodes, the concentrated ions are desorbed from the negativeelectrode and the positive electrode. Since the CapDI device does notuse a high potential difference, the energy efficiency is high. TheCapDI device may remove detrimental ions as well as hardness components,when ions are adsorbed onto the electrodes. The CapDI device does notuse a chemical to regenerate the electrodes, and therefore the CapDIdevice has a relatively low environmental impact.

As shown in FIG. 1, CEDI and ED devices may include a plurality ofadjacent cells or compartments that are separated by selectivelypermeable membranes that allow the passage of either positively ornegatively charged species, but typically not both. Dilution ordepletion compartments are typically interspaced with concentrating orconcentration compartments in such devices. In some embodiments, a cellpair may refer to a pair of adjacent concentrating and dilutingcompartments. As water flows through the depletion compartments, ionicand other charged species are typically drawn into concentratingcompartments under the influence of an electric field, such as a DCfield. Positively charged species are drawn toward a cathode, typicallylocated at one end of a stack of multiple depletion and concentrationcompartments, and negatively charged species are likewise drawn towardan anode of such devices, typically located at the opposite end of thestack of compartments. The electrodes are typically housed inelectrolyte compartments that may be partially isolated from fluidcommunication with the depletion and/or concentration compartments. Oncein a concentration compartment, charged species are typically trapped bya barrier of selectively permeable membrane that may be at leastpartially defining the concentration compartment. For example, anionsmay be prevented from migrating further toward the cathode, out of theconcentration compartment, by a cation selective membrane. Once capturedin the concentrating compartment, trapped charged species can be removedin a concentrate stream.

In CEDI and ED devices, the DC field is typically applied to the cellsfrom a source of voltage and electric current applied to the electrodes(anode or positive electrode, and cathode or negative electrode). Thevoltage and current source (collectively “power supply”) can be itselfpowered by a variety of means such as an AC power source, or forexample, a power source derived from solar, wind, or wave power. At theelectrode/liquid interfaces, electrochemical half cell reactions occurthat initiate and/or facilitate the transfer of ions through themembranes and compartments. For example, in FIG. 1, when a voltage isapplied across the cathode and anode, bicarbonate, calcium, hydroxideand hydrogen ions may form in the solution.

The specific electrochemical reactions that occur at theelectrode/interfaces can be controlled to some extent by theconcentration of salts in the specialized compartments that house theelectrode assemblies. For example, a feed to the anode electrolytecompartments that is high in sodium chloride will tend to generatechlorine gas and hydrogen ion, while such a feed to the cathodeelectrolyte compartment will tend to generate hydrogen gas and hydroxideion. Generally, the hydrogen ion generated at the anode compartment willassociate with a free anion, such as chloride ion, to preserve chargeneutrality and create hydrochloric acid solution, and analogously, thehydroxide ion generated at the cathode compartment will associate with afree cation, such as sodium, to preserve charge neutrality and createsodium hydroxide solution. The reaction products of the electrodecompartments, such as generated chlorine gas and sodium hydroxide, canbe utilized in the process as needed for disinfection purposes, formembrane cleaning and defouling purposes, and for pH adjustmentpurposes.

The performance of electrochemical water treatment devices, especiallyin hard water applications, may be limited by precipitation formed fromhard ions such as calcium and magnesium. When water exceeds thesolubility limit, hard ions, such as calcium and magnesium, drop out ascrystals. One of the methods for determining the solubility limit is theLangelier Saturation Index (LSI). The Langelier Saturation Index(sometimes called the Langelier Stability Index) is a calculated numberused to predict the calcium carbonate stability of water. LSI may becalculated according to a standard method, for example, ASTM D 3739. Theresulting value indicates whether the water will precipitate, dissolve,or be in equilibrium with calcium carbonate.

The Langelier saturation level approaches the concept of saturationusing pH as a main variable. The LSI is expressed as the differencebetween the actual system pH and the saturation pH. LSI can beinterpreted as the pH change required to bring water to equilibrium.Water with an LSI of 1.0 is one pH unit above saturation. Reducing thepH by 1 unit will bring the water into equilibrium. This occurs becausethe portion of total alkalinity present as CO₃ ⁻² decreases as the pHdecreases. For LSI>0, water is super saturated and tends to precipitatea scale layer of CaCO₃. For LSI=0 or close to 0, water is saturated (inequilibrium) with CaCO₃. A scale layer of CaCO₃ is neither precipitatednor dissolved. Water quality, changes in temperature, or evaporationcould change the index. For LSI<0, water is under saturated and tends todissolve solid CaCO₃.

If the actual pH of the water is below the saturation pH, the LSI isnegative and the water has a very limited scaling potential. If theactual pH exceeds the saturation pH, then LSI is positive, and beingsupersaturated with CaCO₃, the water has a tendency to form scale. Atincreasing positive index values, the scaling potential increases.

LSI values are also dependent on temperature, with LSI becoming morepositive as the water temperature increases. This may have particularimplications in situations where well water is used. The temperature ofthe water when it first exits the well is often significantly lower thanthe temperature inside the building served by the well, or inside thelaboratory or process unit where the LSI measurement is made. Theresulting increase in temperature can cause scaling, especially in hotwater heaters. Conversely, systems that reduce water temperature willhave less scaling.

One of the potential problems in electrochemical water treatmentprocesses is the risk of forming insoluble calcium or magnesiumdeposits. These deposits are formed at conditions of high Ca 2⁺ and/orMg 2⁺ concentration and at high pH values. Thus, LSI increases in theconcentrating compartments of electrochemical water treatment devicesdue to the increase in hard ion concentration, or where the water isremoved without reduction of hard ion concentration. Mostelectrochemical water treatment devices are designed to maintain the LSIat values of about 0 to 2. In order to maintain these values, more wateris required in the concentrating compartment, resulting in highervolumes of waste water. This contributes to inefficiencies in operatingthe electrochemical water treatment device.

Frequently, electrochemical water treatment devices are designed toremove as many ions as possible. For many industrial and commercialuses, this highly purified water may be beneficial; however, this levelof purity may be undesirable for other applications, for example, ahousehold water supply, where some level of cation content may bebeneficial. Furthermore, highly purified water may be corrosive and maybe prone to attack copper pipes that are often present in waterdistribution systems. Some water distribution systems may include leadsoldered joints, and heavy metals, such as lead, may also leach intowater passing through the pipes.

As used herein, “hardness” refers to a condition that results from thepresence of polyvalent cations, for example calcium, magnesium, or othermetals, in water, that adversely affect the cleansing capability of thewater and the “feel” of the water, and may increase scaling potential.Hardness is usually quantified by measuring the concentration of calciumand magnesium species. In certain embodiments, undesirable species caninclude hardness ion species.

Electrical conductivity (EC) is a measure of water's ability to “carry”an electrical current, and, indirectly, a measure of dissolved solids orions in the water. Deionized water has a very low conductivity value(nearly zero); hence, the more dissolved solids and ions occurring inthe water, the more electrical current the water is able to conduct. Aconductivity probe in conjunction with a temperature sensor is capableof determining the electrical resistance of a liquid. Fresh waterusually reflects electrical conductivity in units of micro Siemens(μS/cm).

Total Dissolved Solids (TDS) are the total amount of mobile chargedions, including minerals, salts, or metals dissolved in a given volumeof water, expressed in units of mg per unit volume of water (mg/L), alsoreferred to as parts per million (ppm). TDS is directly related to thepurity and quality of water and water purification systems and affectseverything that consumes, lives in, or uses water, whether organic orinorganic. The term “dissolved solids” refers to any minerals, salts,metals, cations or anions dissolved in water, and includes anythingpresent in water other than the pure water (H₂O) molecule and suspendedsolids. In general, the total dissolved solids concentration is the sumof the cations and anions in the water. Parts per million (ppm) is theweight-to-weight ratio of any ion to water. TDS is based on theelectrical conductivity (EC) of water, with pure water having virtuallyno conductivity.

As used herein, the term “system yield” also refers to treatment systemrecovery, meaning the measure of waste versus production. Systemyield/recovery rates are determined using the following calculation:System yield=[Product volume/(Waste volume+Product volume)]*100

The systems and methods described herein are directed to water treatmentor purification systems and methods of providing treated water inindustrial, commercial, residential, and household settings. One or moreembodiments will be described using water as the fluid but should not belimited as such. For example, where reference is made to treating water,it is believed that other fluids can be treated according to the systemsand methods described herein. Moreover, the treatment systems andapparatuses described herein are believed to be applicable in instanceswhere reference is made to a component of the system or to a method thatadjusts, modifies, measures or operates on the water or a property ofthe water. The fluid to be treated may also be a fluid that is a mixturecomprising water.

In at least one aspect, the systems and methods described herein providepurified or treated water from a variety of source types. Possible watersources include well water, surface water, municipal water, and rainwater. The treated product may be for general use or for humanconsumption or other domestic uses, for example, bathing, laundering,and dishwashing. As used herein, the term “treated” in reference towater or fluid, references water exhibiting properties that are suitablefor residential or commercial applications. For example, in certainembodiments, treated water may have a conductivity in a range of fromabout 100 to about 400 μS/cm. In some embodiments, treated water mayhave a conductivity in a range of from about 250 to about 350 μS/cm. Insome embodiments, the treated water may have an alkalinity in a range offrom about 50 to about 200 ppm. In certain embodiments, the treatedwater may have an alkalinity in a range of from about 50 to about 150ppm. In even other embodiments, the treated water may have an alkalinityin a range of from about 80 to about 120 ppm. In one or moreembodiments, treated water may have a hardness in a range of from about1 to about 10 gpg. According to some embodiments, treated water may havea hardness in a range of from about 1 to about 5 gpg. In certain otherembodiments, treated water may have a hardness of about 4 gpg. Theconductivity, alkalinity, and hardness of the treated water may be anyvalue or range of values for these respective properties that issuitable for a desired residential and commercial application, and maybe specifically tailored for a specific use or user.

In another aspect, the systems and methods described herein may beoperated to reduce the likelihood of formation of any scale or foulantsthat are generated while producing treated water. The formation of scaleor foulants in the treatment system, including its components, such aspumps, valves, and fluid lines, may be inhibited by substituting theflowing liquid from one having a high tendency to form scale to a liquidhaving a low to small tendency to produce scale, such as water having alow LSI.

The treatment system in accordance with one or more embodiments mayreceive water from a source and subsequently pass it through a treatmentprocess to produce a product stream possessing targeted characteristics.The treatment system may have a water storage system in fluidcommunication with at least one or more treatment devices. Non-limitingexamples of suitable treatment device may include: electrochemical watertreatment devices, reverse osmosis devices, electrodialysis devices, ionexchange resin devices, capacitive deionization devices, microfiltrationdevices, and/or ultrafiltration devices.

In accordance with one or more embodiments a water treatment system fora residential or commercial application is provided. In someembodiments, the water treatment system includes an electrochemicalwater treatment device. The electrochemical water treatment device mayinclude at least one ion exchange membrane. The at least one ionexchange membrane may be an anion exchange membrane, a cation exchangemembrane, or a combination of both. For example, the device may includea series of alternating anion and cation exchange membranes. Theelectrochemical water treatment device may further comprise at least onecompartment to house the ion exchange membrane(s). In certainembodiments, the electrochemical water treatment device may include aplurality of alternating depleting compartments and concentratingcompartments positioned between a pair of electrodes. The pair ofelectrodes may be a cathode and an anode. The water treatment system mayinclude a concentrate stream and a dilution stream. The concentratestream and dilution stream may be in fluid communication with at leastone ion exchange membrane. In certain embodiments, the at least one ionexchange membrane may be configured to provide a ratio of a pH of theconcentrate stream and a pH of the dilution stream to be less than about1.0. This may be possible due to one or more properties orcharacteristics of the ion exchange membrane(s) used to create theconcentrate and dilution streams. For example, the ion exchangemembranes may be configured to produce a dilution stream that has a pHthat is consistently higher than a pH of the concentrate stream.

In at least one aspect, the systems and methods described herein providea concentrate stream that may circulate through the electrochemicalwater treatment device. In certain aspects, the concentrate stream mayhave an LSI that inhibits scale formation. For example, the concentratestream may have an LSI of less than or about 1, less than or about 0.5,or less than or about 0.2. In at least one aspect, the LSI of theconcentrate stream may be about 0.2.

In some embodiments, the systems and methods described herein mayprovide liquids, such as water, having certain desired propertiesrelated to conductivity, alkalinity, pH, TDS and LSI. For example, thedilution stream may have a conductivity in a range of from about 250 toabout 350 μS/cm. In various embodiments, the conductivity of thedilution stream may be about 300 μS/cm. In one or more embodiments, thedilution stream may have a pH that is greater than 7.0. In someembodiments, the dilution stream may have a pH in a range of from about7.0 to about 8.0. In various embodiments, the dilution stream may havean alkalinity in a range of from about 80 ppm to about 150 ppm. Forexample, the dilution stream may have an alkalinity in a range of fromabout 90 ppm to about 120 ppm. In some embodiments, the dilution streammay have an alkalinity of about 100 ppm. In multiple embodiments, thewater treatment system may be configured to produce a dilution streamwith a hardness of about 4 gpg.

In one or more embodiments, the water treatment system does not requirea separate source of acidic water for the concentrate stream, as may bethe case for other types of water treatment systems. The separate sourceof acidic water may be necessary in other types of systems to maintain adesired pH of the concentrate stream. For example, other types ofsystems may require a separate cation exchange device that is in fluidcommunication with the concentrate stream. The cation exchange devicemay provide an intermittent or continuous supply of acidic water to theconcentrate stream. This requirement may increase the cost andmaintenance of the overall system. The water treatment systems describedherein therefore offer the advantage of not requiring this type ofequipment, thus minimizing or eliminating these additional costs.

In at least one embodiment, the water treatment system does not requirea reverse polarity cycle. As will be appreciated by one of ordinaryskill in the art, a controller may reverse the direction of the appliedfield from a power source to the electrochemical water treatment deviceaccording to a predetermined schedule or according to an operatingcondition, such as water quality, or any other operating parameter inthe treatment system. The function of the concentrating and depletingcompartments is also switched, as well as the functionality of therespective concentrate and dilution streams. Performing a reversepolarity cycle may add additional time, costs, complexity, and size tothe system. The water treatment systems described herein thus allow adistinct advantage over other types of systems that may require reversepolarity cycles as part of the operating process.

Various aspects of the water treatment systems and methods disclosedherein may provide operationally cost effective advantages over othersystems currently available on the market. For example, with referenceto FIG. 4, and as will be discussed in further detail below, theelectrochemical water treatment device may be capable of providing thesame treated water (for example, provide water with a hardness of 4gpg), but the process may be much shorter in duration. This efficiencymay be linked to a characteristic of the ion exchange membranes that areused in the electrochemical water treatment device. For example, themembranes may be particularly selective to calcium, thus affectinghardness, and the speed at which the feed water is cleaned. Further, theLSI of the concentrate stream may be very low (for example, 0.1-0.2),keeping scaling to a minimum without the requirement for any additionalequipment or materials. This benefit may also be attributed to one ormore characteristics of the ion exchange membranes. For example, themembranes may be particularly less selective to bicarbonate, thusaffecting the alkalinity and the subsequent pH.

In various embodiments, the ion exchange membranes may possessproperties related to selectivity of one or more ions. For example, themembranes may be selective toward calcium and de-selective towardbicarbonate. This may contribute toward one or more advantages of thedisclosed system over other types of water treatment systems. Forexample, other systems may require an additional source of acidic waterto maintain or provide a low pH in the concentrate stream, and mayrequire periodic reverse polarity cycling to maintain certain levels ofoperating efficiencies. The elimination of these additional pieces ofequipment and processes may allow the disclosed electrochemical watertreatment devices to decrease processing time, reduce module size,reduce module duty cycle, increase production rate, and reduce the cost,complexity, and size of the overall system.

In accordance with one or more embodiments, a method of treating waterfor a residential or commercial application is provided. The method mayinclude feeding water from a point of entry to an electrochemical watertreatment device. In some instances, the feed water may have aconductivity of at least about 1000 μS/cm. The point of entry mayinclude water from any one of the water sources previously discussed.The method may further comprise passing the feed water through theconcentrating and diluting compartment of the electrochemical watertreatment device to produce a concentrate stream and a product stream.In certain instances, the product stream may have a conductivity ofabout 300 μS/cm. In at least one embodiment, a ratio of a pH of theconcentrate stream to a pH of the product stream is less than about 1.0.In other embodiments, the ratio of the pH of the concentrate stream tothe pH of the product stream is about 0.9. In at least one embodiment,the method comprises recirculating the concentrate stream. According tosome embodiments, the pH of the recirculating concentrate stream is lessthan or about 7.0. The method may further comprise calculating an LSI ofthe concentrate stream. In some embodiments, the LSI of the concentratestream is less than about 1.0. In further embodiments, the LSI of theconcentrate stream is less than or about 0.5. According to some aspects,the method further comprises storing at least a portion of the productstream and measuring a conductivity, an alkalinity, and a pH of thestored portion of the product stream. According to at least oneembodiment, the conductivity, the alkalinity, and the pH of the storedportion of the product stream are about 300 μS/cm, about 100 ppm, andgreater than about 7.0, respectively. In certain aspects, the methodfurther comprises calculating an LSI of the concentrate stream. In atleast one example, the LSI of the concentrate stream is about 0.2. Invarious embodiments, the method does not require the addition of aseparate source of acidic water to the concentrate stream. In certainembodiments, the method does not require a reverse polarity cycle.

According to one or more aspects, the electrochemical water treatmentdevice may include at least one ion exchange membrane. The ion exchangemembranes may include anion and cation exchange membranes. In variousaspects, ion exchange membranes may have low electrical resistance, highpermselectivity, high chemical stability, and high mechanical strength.In at least one aspect, an ion exchange membrane may have a resistivityof less than about 1.5 Ohm-cm² and an apparent permselectivity of atleast about 95%. Ion exchange membranes that are suitable for use in thesystems and methods disclosed herein are available from Evoqua WaterTechnologies.

The electrical resistivity of an ion exchange membrane is generally anexpression of how strongly the membrane resists the flow of electriccurrent. When resistivity is high, more current, and thus more energy,may need to be applied to the electrochemical cell to facilitate iontransfer across the membrane to perform the desired electrochemicalseparation process. As used herein, the terms “electrical resistance”and “electrical conductivity” may be used interchangeably and refer tothe resistance of a material to the flow of electrical current and maybe expressed as electrical resistance per unit area (Ω cm²). Theelectrical resistance of a membrane may be determined by theion-exchange capacity and the mobility of an ion within a membranematrix. In general, electrical resistance is proportional to ionconcentration, meaning that electrical resistance increases withincreasing ion concentration. Thus, in general, the lower theresistivity of the ion exchange membrane, the more efficient themembrane. In electrochemical processes, it may be desirable to use ionexchange membranes with low electrical resistance, since they may saveenergy and reduce ohmic losses during operation.

As used herein, the term “permselectivity” refers to an ion exchangemembrane's ability to be permeable to one chemical species butimpermeable with respect to another chemical species. For example, incertain instances the ion exchange membrane may be permeable tocounter-ions, but impermeable to co-ions. This means, for example, thatwhen an electric current is applied to an electrochemical cell havingboth anion and cation exchange membranes, cations in solution will crossthe cation membrane but anions will not cross. When, as in this example,anions are allowed to cross the cation membrane, the overall efficiencyof the process is reduced. In certain instances it may be desirable tohave membranes with a high permselectivity, where the membranes arehighly permeable to counter-ions and highly impermeable to co-ions.

The ion exchange membrane may be constructed from a polymeric substratethat is covered by a polymeric layer. In various aspects, the polymericlayer may be cross-linked. In at least one embodiment, the cross-linkedpolymeric layer may react with the polymeric substrate to yield ahydrophobic surface.

The ion exchange membranes may comprise polymeric materials thatfacilitate the transport of either positive or negative ions across themembrane. Ion exchange membrane properties, including resistivity andpermselectivity, may be controlled, in part, by the amount, type, anddistribution of fixed ionic groups in the membrane. For example, strongbase anion exchange membranes may generally comprise quaternary amines,and weak base anion exchange membranes may generally comprise tertiaryamines. The amines may have fixed positive charges that allow anionicspecies to permeate across the membrane.

In various embodiments, the ion exchange membranes may be generallyheterogeneous membranes. The heterogeneous membranes may include apolymeric layer that is coated on top of a substrate and the polymericlayer may provide fixed charges on the outer surface of the membrane. Inother embodiments, the ion exchange membranes may be generallyhomogeneous. Homogeneous membranes may be produced by the polymerizationof monomers and may include a polymeric microporous substrate. Reactivemonomers may be used to fill the pores of the substrate, yielding amembrane with a highly uniform microstructure. The reactive monomers maybe selected to functionally remove specific ions. For example, thereactive monomer may be selected to remove bicarbonate.

In one or more aspects, the methods and systems described herein providetreated water while decreasing the ionic load discharged from thetreatment system. For example, the total amount of waste waterdischarged as a result of the treatment process may be significantlyless than conventional treatment processes, and may be less than 25%,less than 20%, or less than 10% of the total volume of water treated.

One or more embodiments of the treatment systems disclosed here mayinclude one or more fluid control devices, such as pumps, valves,regulators, sensors, pipes, connectors, controllers, power sources, andany combination thereof.

In accordance with one or more embodiments, the treatment systemsdisclosed here may comprise one or more pumps. A variety of pumps forpumping and/or circulating fluid may be used in conjunction with thetreatment system. Pumps may be internal and/or external to one or moreof the components of the treatment system, and/or may be otherwiseintegrated with the treatment system. Non-limiting examples of pumpsinclude electrical pumps, air driven pumps, and hydraulic pumps. Thepump may be driven by a power source that can be any conventional powersource, for example, gasoline driven motors, diesel driven motors,solar-powered motors, electric motors, and any combination thereof.

In accordance with one or more embodiments, the methods and systemsdisclosed here further comprise one or more valves. Non-limitingexamples of valves suitable for control according to one or moreembodiments include, but are not limited to, check valves, gate valves,bypass valves, solenoid valves, other types of hydraulic valves, othertypes of pneumatic valves, relief valves, and any combination thereof.Suitable valves include one-way and/or multi-way valves. In certainnon-limiting embodiments, the valve can be a pilot valve, a rotaryvalve, a ball valve, a diaphragm valve, a butterfly valve, a fluttervalve, a swing check valve, a clapper valve, a stopper-check valve, alift-check valve, and any combination thereof. The valves may bemanually actuated (for example, by an operator) and/or hydraulically,pneumatically, solenoid, or otherwise actuated, including controlactuated by a process controller or control system. The valves may be anon/off type of valve, or may be a proportional type of valve.

The treatment system, in some embodiments of the systems and methodsdescribed herein, further comprises one or more sensors or monitoringdevices configured to measure at least one property of the water or anoperating condition of the treatment system. Non-limiting examples ofsensors include composition analyzers, pH sensors, temperature sensors,conductivity sensors, pressure sensors, and flow sensors. In certainembodiments, the sensors provide real-time detection that reads, orotherwise senses, the properties or conditions of interest. A fewnon-limiting examples of sensors suitable for use in one or moreembodiments include optical sensors, magnetic sensors, radio frequencyidentification (RFID) sensors, Hall effect sensors, and any combinationthereof.

In one or more embodiments, an RFID antenna can be used to providepositional and other information regarding the treatment system, such asone or more water properties. The RFID antenna senses the targetedinformation and an associated RFID antenna control processor cantransmit the information to a system processor, thereby providing onemethod of in-line real-time process control.

In certain non-limiting embodiments of the systems and methods describedherein, the treatment system further comprises a flowmeter for sensingthe flow of fluid. A non-limiting example of a flowmeter suitable forcertain aspects of the treatment system disclosed here includes a Halleffect flowmeter. Other non-limiting examples of flowmeters suitable forcertain aspects of the treatment system include mechanical flowmeters,including a mechanical-drive Woltman-type turbine flowmeter.

According to one or more aspects, the systems and methods disclosedherein may include a control system disposed or configured to receiveone or more signals from one or more sensors in the treatment system.The control system can be further configured to provide one or moreoutput or control signals to one or more components of the treatmentsystem. One or more control systems can be implemented using one or morecomputer systems. The computer system may be, for example, ageneral-purpose computer such as those based on an Intel PENTIUM®-typeprocessor, a Motorola PowerPC® processor, a Sun UltraSPARC® processor, aHewlett-Packard PA-RISC® processor, or any other type of processor orcombinations thereof. Alternatively, the computer system may includePLCs, specially-programmed, special-purpose hardware, for example, anapplication-specific integrated circuit (ASIC), or controllers intendedfor analytical systems.

In some embodiments, the control system can include one or moreprocessors connected to one or more memory devices, which can comprise,for example, any one or more of a disk drive memory, a flash memorydevice, a RAM memory device, or other device for storing data. The oneor more memory devices can be used for storing programs and data duringoperation of the treatment system and/or a control subsystem. Forexample, the memory device may be used for storing historical datarelating to the parameters over a period of time, as well as currentoperating data. Software, including programming code that implementsembodiments of the systems and methods disclosed herein, may be storedon a computer readable and/or writeable nonvolatile recording medium,and then copied into the one or more memory devices where it can then beexecuted by the one or more processors. Such programming code may bewritten in any of a plurality of programming languages, for example,ladder logic, Java, Visual Basic, C, C#, or C++, Fortran, Pascal,Eiffel, Basic, COBOL, or any of a variety of combinations thereof.

Components of a control system may be coupled by one or moreinterconnection mechanisms, which may include one or more busses, forexample, between components that are integrated within a same device,and/or one or more networks, for example, between components that resideon separate discrete devices. The interconnection mechanism enablescommunication, for example, data, instructions, to be exchanged betweencomponents of the system.

The control system can further include one or more input devices, forexample, a keyboard, mouse, trackball, microphone, touch screen, and oneor more output devices, for example, a printing device, display screen,or speaker. In addition, the control system may contain one or moreinterfaces that can connect to a communication network, in addition toor as an alternative to the network that may be formed by one or more ofthe components of the control system.

According to one or more embodiments, one or more input devices mayinclude one or more sensors for measuring the one or more parameters ofthe fluids in the treatment system. Alternatively, the sensors, themetering valves and/or pumps, and/or all of these components, may beconnected to a communication network that is operatively coupled to acontrol system. For example, sensors may be configured as input devicesthat are directly connected to the control system. Additionally,metering valves and/or pumps of the one or more sources of treatingcompositions may be configured as output devices that are connected tothe control system, and any one or more of the above may be coupled toanother ancillary computer system or component so as to communicate withthe control system over a communication network. Such a configurationpermits one sensor to be located at a significant distance from anothersensor or allows any sensor to be located at a significant distance fromany subsystem and/or the controller, while still providing datatherebetween.

In certain embodiments, a computer can be coupled to a server and to aplurality of different input devices. The input devices may include, forexample, a wireless communication device (for example, a radio frequencyidentification (RFID) antenna), one or more sensors, a touch screenhaving a virtual keyboard, and one or more monitoring devices. Forpurposes of this disclosure, the term “monitoring” may be defined toinclude, in a non-limiting manner, acts such as recording, observing,evaluating, identifying, etc. In addition, the RFID antenna, any of thesensors, and/or the touch screen, may be configured to operate both asinput devices and/or output devices. The touch screen is optional andmay alternatively include other known input devices such as a keyboard,mouse, touch pad, joystick, remote control (either wireless or with awire), track ball, mobile device, etc.

In certain non-limiting embodiments, a computer is wirelessly coupled toa server and an RFID antenna and one or more other sensors. The RFIDantenna may receive input from an RFID device, such as a tag device,secured or otherwise in communication to one or more components of thetreatment system. The RFID device can be programmed to include a widerange of information, and additional monitoring information collectedduring one or more water treatment cycles can be added to the RFIDdevice. When the RFID device is in communication with the RFID antenna,any information programmed into the RFID device can be downloaded ontothe computer and transferred to the server. The RFID device may alsoinclude an encryption device.

The control system can include one or more types of computer storagemedia such as readable and/or writeable nonvolatile recording medium inwhich signals can be stored that define a program to be executed by oneor more processors. The storage or recording medium may be, for example,a disk or flash memory. In operation, the processor can cause data, suchas code that implements one or more embodiments of the systems andmethods disclosed herein, to be read from the storage medium into amemory device that allows for faster access to the information by theone or more processors. The memory device is a volatile, random accessmemory such as a dynamic random access memory (DRAM), or static memory(SRAM), or any other suitable devices that facilitate informationtransfer both to and from the one or more processors.

In certain embodiments, the treatment system also includes a controllerfor adjusting, monitoring, or regulating at least one operatingparameter and its components of the treatment system. A controllercomprises a microprocessor-based device, such as a programmable logiccontroller (PLC) or a distributed control system that receives or sendsinput and output signals to one or more components of a treatmentsystem. In certain embodiments, the controller regulates the operatingconditions of the treatment system in an open-loop or closed-loopcontrol scheme. For example, the controller, in open-loop control, canprovide signals to the treatment system such that water is treatedwithout measuring any operating conditions. The controller can alsocontrol the operating conditions in closed-loop control so that any oneor more operating parameters can be adjusted based on an operatingcondition measured by, for example, a sensor. In yet another embodiment,the controller can further comprise a communication system, for example,a remote communication device, for transmitting or sending the measuredoperating condition or operating parameter to a remote station.

The controller, or components or subsections thereof, may alternativelybe implemented as a dedicated system or as a dedicated programmablelogic controller (PLC) in a distributed control system. Further, itshould be appreciated that one or more features or aspects of thesystems and methods disclosed herein may be implemented in software,hardware or firmware, and any combination thereof. For example, one ormore segments of an algorithm executable by the one or more controllerscan be performed in separate computers, which in turn, can becommunicated through one or more networks.

FIG. 2 is a process flow diagram of a water treatment system 20 inaccordance with one or more embodiments. The water treatment systemincludes an electrochemical water treatment device 200. Electrochemicalwater treatment device 200 may have a series of alternating cation andanion exchange membranes positioned between a cathode and anode. Thetreatment system may further include a concentrate stream 210 anddilution stream 230 that are in fluid communication with at least oneion exchange membrane in the electrochemical water treatment device 200.The concentrate and dilution streams may also be in fluid communicationwith a manifold (not shown), which functions to collect liquid exitingfrom one or more compartments of the electrochemical water treatmentdevice 200. For example, a storage tank 240 may be in fluidcommunication with the dilution stream 230 and function to store treatedwater 260 for further use. Concentrate stream 210 and dilution stream230 may also be in fluid communication with a pump 250 that functions tocirculate the respective streams throughout the water treatment system20. Water treatment system 20 may further include a reject or wastestream 220 and a reject make-up stream 270 that are in fluidcommunication with the concentrate stream 210.

FIG. 3 is another process flow diagram of a treatment system 30according to one or more embodiments. A liquid circuit is illustratedwhere a feed stream 304 is introduced to treatment system 30. The feedstream 304 may provide or be in fluid communication with a water source.Non-limiting examples of the water source include potable water sources,for example, municipal water, well water, non-potable water sources, forexample, brackish or salt-water, pre-treated semi-pure water, and anycombination thereof. In some instances, a treatment system, for example,a purification system, and/or a chlorine removal system, treats thewater before it comprises the feed stream. The feed stream may containdissolved salts or ionic or ionizable species including sodium,chloride, chlorine, calcium ions, magnesium ions, carbonates, sulfatesor other insoluble or semi-soluble species or dissolved gases, such assilica and carbon dioxide. The feed stream may also contain additives,such as fluoride, chlorate, and bromate species.

In accordance with one or more embodiments, treatment system 30 includesa fluid distribution system. The distribution system comprisescomponents that are fluidly connected to provide fluid communicationbetween components of the treatment system, for example, providing fluidcommunication between treated water from storage system 380, to productstream 360. The distribution system can comprise any arrangement ofpipes, valves, tees, pumps, manifolds, and any combination thereof, toprovide fluid communication throughout treatment system 30 andthroughout one or more product streams or storage systems available to auser. In certain embodiments, the distribution system further comprisesa household or residential water distribution system including, but notlimited to, connections to one or more points of use such as, a sinkfaucet, a showerhead, a washing machine, and a dishwasher. For example,treatment system 30 may be connected to the cold, hot, or both, waterdistribution systems of a household. Pumps and vacuum sources may be influid communication with various components of the fluid distributionsystem for purposes of controlling liquid flow by pressurizing theliquid. The pressurized liquid stream may further comprise a regulatorwhere the pressure can be more readily controlled. Fluid may also becaused to flow by gravity.

The liquid circuit may further comprise one or more bypass valves 312which may allow liquid to flow through one part of water treatmentsystem 30 and prevent flow through another part of the system. Forexample bypass valve 312 may function to allow fluid from feed stream304 to bypass water treatment system 30 and exit with product stream360, or conversely allow feed stream 304 to flow into the watertreatment system through valve 302, flowmeter 316, and pre-filter 305.

Pre-filter device 305 may be a preliminary filter or pre-treatmentdevice designed to remove a portion of any undesirable species from thewater before the water is further introduced into one or more componentsof treatment system 30. Non-limiting examples of pre-filter devicesinclude, for example, carbon or charcoal filters that may be used toremove at least a portion of any chlorine, including active chlorine, orany species that may foul or interfere with the operation of any of thecomponents of the treatment system process flow. Additional examples ofpre-treatment devices include, but are not limited to, ionic exchangedevices, mechanical filters, and reverse osmosis devices. Pre-treatmentsystems can be positioned anywhere within treatment system 30. Forexample, water that enters storage system 380 after being treated byelectrochemical water treatment device 300 may contain little or nochlorine (or any other alternative disinfectant). To retain a residualchlorine level in storage system 380, the water can be mixed withuntreated water from feed stream 304. Preferably, the chlorinated wateris added at a rate adequate to result in mixed water that containsenough chlorine to inhibit bacteriologic activity. Active chlorinerefers to chlorine containing species that exhibit anti-microbialactivity. An effective chlorine concentration is defined herein as aconcentration of active chlorine compounds, for example, sodiumhypochlorite that inhibits the growth of bacteria, such as e-coli, instorage system 380. Therefore, the ratio at which the feed water andtreated water are mixed in storage system 380 may be dependent upon anumber of factors, including the efficiency of electrochemical watertreatment device 300, the desired effective chlorine concentration, therate at which water contained in storage system 380 is depleted, thetemperature of storage system 380, and the source and quality of thefeed water. Pre-treatment devices may also be, for example, aparticulate filter, aeration device, or a chlorine-reducing filter, andmay comprise several devices, or a number of devices arranged inparallel or in a series. Pre-treatment device 305 can be positionedupstream or downstream of the storage system 380, or positioned upstreamof electrochemical water treatment device 300 so that at least somechlorine species are retained in the storage system 380 but are removedbefore water enters the electrochemical water treatment device 300.

In accordance with certain embodiment of the systems and methodsdescribed herein, treatment system 30 may also comprise one or moreprobes or sensors 306, for example, a water property sensor, capable ofmeasuring at least one physical property in treatment system 30. Forexample, the sensor 306 can be a device that measures waterconductivity, pH, temperature, pressure, composition, and/or flow rates.The probe or sensor can be installed or positioned within treatmentsystem 30 to measure a particularly preferred water property. Forexample, a probe or sensor 306, can be a water conductivity sensorinstalled in or otherwise placed in fluid communication with storagesystem 380 so that it measures the conductivity of the water. This mayprovide an indication of the quality of water available for productstream 360. In another embodiment, the probe or sensor can comprise aseries or a set of sensors in various configurations or arrangements intreatment system 30. The set of sensors can be constructed, arranged,and connected to a controller so that the controller can monitor,intermittently or continuously, the quality of water in, for example,storage system 380. This arrangement allows the performance of treatmentsystem 30 to be further optimized.

In accordance with other embodiments of the systems and methodsdescribed herein, treatment system 30 may include a combination of setsof sensors in various locations in the liquid streams or othercomponents throughout treatment system 30. For example, the probe orsensor can be a flow sensor measuring a flow rate from feed stream 304,and can further include any one or more of a pH meter, a nephelometer, acomposition analyzer, a temperature sensor, and a pressure sensormonitoring the operating conditions of treatment system 30.

Storage system 380 may store or accumulate water from feed stream 304and may also serve to store treated water for product stream 360 and mayfurther provide water to electrochemical water treatment device 300. Inaccordance with some embodiments of the systems and methods describedherein, storage system 380 comprises a tank, vessel or reservoir thathas inlets and outlets for fluid flow. In certain non-limitingembodiments, the storage system comprises a tank that has a volumecapacity in a range of from about 5 gallons to about 200 gallons. Incertain non-limiting embodiments, storage system 380 may compriseseveral tanks or vessels, and each tank or vessel, in turn, may haveseveral inlets and/or outlets positioned at various locations. Theinlets and outlets may be positioned on each vessel at various locationsdepending on, among other things, the demand and flow rate to productstream 360, the capacity or efficiency of electrochemical watertreatment device 300, and the capacity or hold-up of storage system 380.

Storage system 380 may further comprise various components or elementsthat perform desirable functions or avoid undesirable consequences. Forexample, the tanks or vessels may have internal components, such asbaffles, that are positioned to disrupt any internal flow currents orareas of stagnation. In some embodiments, storage system 380 furthercomprises a heat exchanger for heating or cooling the stored fluid. Forexample, storage system 380 may comprise a vessel constructed with aheating coil, which can have a heating fluid at an elevated temperaturerelative to the temperature of the fluid in the vessel. The heatingfluid can be hot water in a closed-loop flow with a furnace or otherheat-generating unit so that the heating fluid temperature is raised inthe furnace. The heating fluid, in turn, raises the vessel fluidtemperature by heat transfer. Other examples of auxiliary or additionalcomponents include, but are not limited to, pressure relief valvesdesigned to relieve internal pressure in the storage system. Inaccordance with further embodiments, the treatment system can compriseat least two tanks or vessels or two zones in one or more tanks orvessels, each of which can be, at least partially, fluidly isolated fromthe other. For example, the treatment system can comprise two vesselsfluidly connected to a feed stream and to one or more treatment devices.The two tanks or vessels can be fluidly isolated from each other byconduits and valves so that the first can be placed in service with oneor more treatment devices while the second can be removed from servicefor, for example, maintenance or cleaning. In accordance with one ormore embodiments of the systems and methods described herein, the tankor reservoir system is connected to, or in thermal communication with, aheat exchanger and, optionally, to a fluid treatment device. The fluidtreatment device can be an electrochemical water treatment device, areverse osmosis device, an ion-exchange resin bed, an electrodialysisdevice, a capacitive deionization device, or combinations thereof.

In certain embodiments, liquid exiting electrochemical water treatmentdevice 300 as dilution stream 330 may be directed by valve 312 tostorage system 380. In addition, storage system 380 may store oraccumulate water from feed stream 304. Thus, storage system 380 mayinclude treated water as well as untreated, or minimally treated, water.Storage system 380 may be configured so that these two sources of waterare mixed together, or alternatively, the two water sources may besegregated. For example, one source of water may enter the bottom ofstorage system 380 through one or more inlets and proceed in plug-flowmanner in an upward direction to one or more outlets positioned at thetop of storage system 380.

In various embodiments, a dilution stream 330 may flow in a circulatingloop through electrochemical water treatment device 300. The circulatingdilution stream may provide fluid communication between one or moredepletion compartments in electrochemical water treatment system 300 andstorage system 380. Likewise, a concentrate stream 310 may flow in acirculating loop through electrochemical water treatment device 300 andmay be in fluid communication between one or more concentrationcompartments in electrochemical water treatment device.

Water treatment system 30 may further include one or more gate valves302 and flow meters 308. For example, the fluid path flowing fromstorage system 380 to product stream 360 may include gate valve 302,flow meter 308, and one or more sensors 306, for example, an ionicconductivity probe. In one or more embodiments, concentrate stream 310may include water from concentrate make-up stream 314 that is fed fromfeed stream 304 and passes through pre-filter 305. A valve (not shown)may be positioned at the junction of the concentrate make-up stream 314and concentrate stream 310.

In certain non-limiting embodiments, the valve 312 may be a solenoidvalve. The solenoid valve may be a one-way or multi-way valve, includingthree-way and four-way valves. The solenoid valve may be an on/off typeof valve, a proportional type of valve, and any combination thereof. Forexample, a four-way solenoid valve 312 may include a first port that isin fluid communication a concentrate compartment of electrochemicalwater treatment device. A second port may be in fluid communication witha dilution compartment of electrochemical water treatment device 300. Asecond four-way solenoid valve 312 may be positioned downstream of oneor more outlets of electrochemical water treatment device 300. Forexample, a first and second port of valve 312 may be in fluidcommunication with an outlet of a concentrate and dilution chamber ofelectrochemical water treatment device 300, and feed the concentratestream and dilution stream respectively.

In one or more embodiments, a control system may be in communicationwith a multi-way valve. For example, a three-way solenoid valve mayallow either one of two incoming fluids to be directed to an outlet.When the valve is in the “off” position, fluid flow from one of theincoming fluid streams may be interrupted. When the valve is in the “on”position fluid flow from the other incoming fluid stream may beinterrupted. For example, valve 312 may be used to direct fluid flowfrom concentrate stream 310 and storage system 380 to electrochemicaltreatment device 300. The exact selection of which or both of thesestreams may be used may be controlled by one or more components of thecontrol system.

Treatment system 30 may further comprise a liquid circuit that allowsfluid communication between one or more outlets of electrochemical watertreatment device 300, and storage system 380. For example, a third portof valve 312 may be in fluid communication with at least one outlet ofelectrochemical water treatment device 300. In certain embodiments, theoutlet of the electrochemical water treatment device comprisesion-depleted water from one or more depletion compartments ofelectrochemical water treatment device 300. A fourth port of valve 312may be in fluid communication with a sensor 306, for example, an ionicconductivity probe. The liquid circuit may also be in fluidcommunication with at least one inlet to storage system 380. An outletof storage system 380 may be in fluid communication with at least oneinlet to electrochemical water treatment device 300. The liquid circuitmay include one or more pumps 350 to aid in directing fluid throughoutthe treatment system 30, for example, for directing fluid into one ormore inlets of electrochemical water treatment device 300.

The systems and methods described herein further provide a treatmentsystem where a controller may provide a signal that actuates a valve sothat fluid flow is adjusted based on a variety of operating parameters.These parameters may include, but are not limited to, the properties ofwater from feed stream 304, the properties of water in storage system380, the properties of water in dilution stream 330, the properties ofwater in concentrate stream 310, and any combination thereof. Otherparameters may include the properties of water exiting storage system380, the demand of water necessary to provide to product stream 360, theoperating efficiency or capacity of electrochemical water treatmentdevice 300, the operating parameters associated with electrochemicalwater treatment device 300, and any combination thereof. Specificmeasured parameters may include, but are not limited to, waterconductivity, pH, turbidity, composition, temperature, pressure, flowrate, and any combination thereof.

In one or more embodiments, a controller may receive signals from one ormore sensors so that the controller is capable of monitoring theoperating parameters of treatment system 30. For example, a conductivitysensor may be positioned within storage system 380 so that theconductivity is monitored by the controller. In one or more embodiments,a controller may receive a signal from one or more sensors so that thecontroller is capable of monitoring the operating parameters of thedilution stream, such as conductivity. In operation, the controller mayincrease, decrease, or otherwise adjust the voltage, current, or both,supplied from a power source to one or more components of the treatmentsystem. The controller may include algorithms that may modify anoperating parameter of treatment system 30 based on one or more measuredproperties of the liquid flowing in the system. For example, in someembodiments, the controller may increase or decreases the flow rate ofthe concentrate stream 310 and the dilution stream 330.

The controller may be configured, or configurable by programming, or maybe self-adjusting such that it is capable of maximizing any of theservice life, the efficiency, or reducing the operating cost oftreatment system 30. For example, the controller may include amicroprocessor having user-selectable set points or self-adjusting setpoints that adjust the applied voltage, current, or both, to valve(s)312, the flow rate through concentrate stream 310, and the flow rate outto discharge stream 320.

In accordance with another embodiment of the systems and methodsdescribed herein, the controller regulates the operation of thetreatment system by incorporating adaptive or predictive algorithms,which are capable of monitoring demand and water quality and adjustingthe operation of any one or more components of the treatment system 30.For example, in a residential application, the controller may bepredictive in anticipating higher demand for treated water during earlymorning hours to supply product stream 360 that services a showerhead.

In certain non-limiting embodiments, radio frequency identification(RFID) is utilized to provide real-time detection of certain propertiesor conditions in treatment system 30. In certain embodiments, aplurality of inline identifying tag readers or optical sensors areconfigured to track or sense certain properties or conditions of theliquid as it is transported through the treatment system. The RFID maybe combined with one or more additional sensors, for example, aflowmeter. For example, an embedded tag may be placed in the cartridgeof pre-filter device 305 and used in combination with a flowmeter todetermine various properties or conditions, for example, the usablevolume remaining in the cartridge, and the number of days remainingbefore the cartridge is exhausted and needs to be replaced.

In certain non-limiting embodiments, valves 312 can be actuated toprovide liquid to be treated from storage system 380 to electrochemicalwater treatment device 300 and transfer the treated liquid to storagesystem 380. In some arrangements, the liquid circuit may includeconnections so that untreated liquid may be mixed with liquid that wouldexit any of the electrode compartments of electrochemical watertreatment device 300. In several embodiments, the liquid circuit mayfurther include connections to and from storage system 380 so that, forexample, treated liquid exiting the depleting compartment ofelectrochemical water treatment device 300 may be transferred to storagesystem 380 and mixed with untreated liquid from feed stream 304. Theresulting mixture may be delivered to product stream 360, and,optionally, to the one or more ion exchange membranes of theelectrochemical water treatment device 300 in parallel or series flowpaths.

In accordance with another embodiment of the systems and methodsdescribed herein, a controller, through a sensor or set of sensors, maymonitor or measure at least one water property of the water storagesystem 380 and also measure a flow rate flowing in product stream 360.The controller may adjust an operating parameter of electrochemicalwater treatment device 300 and/or valve 312 based on the measuredproperties. In one or more embodiments of the systems and methodsdescribed herein, one or more sensors may measure at least one propertyof feed stream 304 and water in storage system 380.

In certain embodiments, storage system 380 may be connected downstreamof feed stream 304 and may be in fluid communication withelectrochemical water treatment device 300. For example, water from feedstream 304 may flow in and mix with the bulk water contained withinstorage system 380. Bulk water may exit storage system 380 and bedirected to product stream 360 or exit through and be directed throughvalve 312 into electrochemical water treatment device 300 for treatment.In certain embodiments, treated water leaving electrochemical watertreatment device 300 may mix with water from feed stream 304 by enteringstorage system 380. In this way, a liquid circuit may be formed betweenstorage system 380, electrochemical water treatment device 300 and feedstream 304, and may function as a method for replenishing the waterleaving the system 30 via product stream 360.

In accordance with further embodiments of the systems and methodsdescribed herein, one or more disinfecting and/or cleaning apparatuscomponents may be utilized with the treatment system. Such disinfectingor cleaning systems can comprise any apparatus that destroys or rendersinactive, at least partially, any microorganisms, such as bacteria, thatcan accumulate in any component of the treatment system. Examples ofcleaning or disinfecting systems include those that can introduce adisinfectant or disinfecting chemical compounds, such as halogens,halogen-donors, acids or bases, as well as systems that expose wettedcomponents of the treatment system to hot water temperatures capable ofsanitization. In accordance with still further embodiments of thesystems and methods described herein, the treatment system may includefinal stage or post treatment systems or subsystems that provide finalpurification of the fluid prior to delivery at a point of use. Examplesof such post treatment systems include, but are not limited to thosethat expose the fluid to actinic radiation or ultraviolet radiation,and/or ozone or remove undesirable compounds by microfiltration orultrafiltration. Thus, the treatment system may be utilized forhousehold service and installed, for example, under a sink and providetreated water that is further treated by exposure to ultravioletradiation before being delivered to a point of use, such as a faucet.

In accordance with further embodiments, the treatment system maycomprise systems and techniques that permit disinfection of anycomponent of the treatment system. For example, the treatment system maybe exposed to a disinfecting solution or a disinfectant. Thedisinfectant may be any material that can destroy or at least renderinactive at least a portion of any viable microorganisms, such asbacteria, present in any component or subsystem of the treatment system.Examples of disinfectants may include bases, acids, or sanitizers, suchas a halogen or halogen-donating compounds and peroxygen orperoxygen-donating compounds that destroy or render bacteria inactive.The disinfectant may be introduced into the treatment system by anysuitable device or technique. For example, chlorine may be introducedinto the storage system. Chlorine may be introduced by injection of ahypochlorate species from a disinfectant reservoir fluidly connectableto any suitable portion of the treatment system. The chlorinated watercan be further circulated through at least a portion of the treatmentsystem thereby exposing wetted portions of the system to thedisinfectant.

In accordance with another embodiment, discharge water comprising, forexample, water exiting the system via waste or reject stream 320 may beused for auxiliary purposes to serve or provide additional or secondarybenefits. For example, discharge water may be used to provide, forexample, irrigating water to residential and commercial, and industrialuses. Discharge water may also be used for recovery of collected orconcentrated salts.

In one or more embodiments, the treatment system may include a mixingsystem that is fluidly connected to at least one of a fluid distributionsystem and a storage system. The mixing or blending system may includeone or more connections in the fluid distribution system as well asconnections to a feed stream. The mixing system may provide fluid mixingof, for example, untreated water with treated water to produce servicewater that may be fed to one or more product streams. For example, themixing system may comprise at least one tee, a mixing tank, or both,that fluidly connects an outlet of the storage system and the feedstream. The mixing system, in some cases, may include a valve thatregulates the flow of any of the untreated water streams, treated waterstreams, and any other stream flowing to the product streams. In anotherembodiment, the valve may be a proportional valve that mixes the treatedwater with untreated water according to a predetermined ratio. Inanother embodiment, the valve may be actuated by a controller based on,for example, the flow rate, the water property, and the particularservice associated with the product stream. For example, if low hardnesswater is required for the product stream, then the controller mayregulate the amount of untreated water, if any, that can be mixed withtreated water by actuating a valve. This may be accomplished by usingclosed-loop control with a sensor measuring the conductivity of themixed water stream. In another embodiment, the valve may regulate theflow rate of the treated water that is mixed with the untreated wateraccording to certain requirements of the product stream. In otherembodiments, the treatment device may be operated to reach a set-pointthat is lower than any required by one or more product streams so thatany mixing of treated water with untreated water can produce servicewater that satisfies the particular requirements of each product stream.

Those of ordinary skill should recognize that the treatment system canbe adjustable to accommodate fluctuations in demand as well asvariations in water quality requirements. For example, the systems andmethods described herein may produce low LSI water that is available tothe treatment system as a whole, during extended idle periods. The lowLSI water, in some embodiments, may be used to flush the wettedcomponents of the treatment system, which may reduce the likelihood ofscaling and increase the service life not only the individualcomponents, but also the treatment system as a whole. In accordance withsome embodiments, the systems and methods described herein provide forproducing treated liquids, such as water, having a low conductivity. Thetreatment system may comprise a fluid circuit that provides treated or,in some cases, softened water or, in other cases, low conductivitywater, and/or low LSI water, to one or more product streams andsubsequently, one or more points of use.

In another embodiment of the systems and methods described herein,treatment system 30 may comprise one or more flow regulators forregulating liquid flow. For example, a flow regulator may regulate thevolume of fluid discharged from the system via a waste stream. Accordingto another embodiment of the systems and methods described herein, theflow regulator may be a valve that may be intermittently opened andclosed according to a predetermined schedule for a predetermined periodof time to allow a predetermined volume of water to flow. The volume offlowing fluid may be adjusted by, for example, changing the frequencyand/or duration that the flow regulator is opened and closed. In someembodiments, the flow regulator may be controlled or regulated by acontroller, through, for example, an actuation signal. The controllermay provide an actuation signal, such as a radio, current or a pneumaticsignal, to an actuator, with a motor or diaphragm that opens and closesthe flow regulator. The fluid regulated by a valve or flow regulator maybe any fluid located in the water treatment system.

EXAMPLE

The function and advantages of these and other embodiments will be morefully understood from the following example. The example is intended tobe illustrative in nature and is not to be considered as limiting thescope of the embodiments discussed herein.

Example 1—Comparison Study

An electrochemical treatment system in accordance with one or moreembodiments of the systems and methods described herein and shownschematically in FIG. 2 was evaluated for performance against a controltreatment system. A comparison study was conducted to evaluate theperformance characteristics for both systems in cleaning a 28 gallonvolume of feed water from 20 gpg to 4 gpg. The feed streams for bothsystems were identical in composition. Water was treated by anelectrochemical device under the conditions outlined in Table 1 below.

TABLE 1 Electrochemical Treatment System Conditions; High EfficiencyElectrodeionization (HEED) Module: 15 cell pairs; 0.065″ cell thicknessfilled with open weave supporting screens Compartment size: 7″ × 7″cross section Flow Rate of all streams 1.5 gpm Applied Voltage 2Volts/cell pair No cycle switching/No requirement for additional sourceof acidic water

In addition, water was treated by a control device (a CEDI device) underthe conditions outlined in Table 2 below.

TABLE 2 Control Treatment System Conditions (CEDI device) Module: 30cell pairs; 0.065″ cell thickness with mixed bed ion exchange resinCompartment size: 7″ × 7″ cross section Flow Rate of all streams 2.0 gpmApplied Voltage 2 Volts/cell pair Requires cycle switching/Requiresadditional source of acidic water to lower pH of concentrate stream

The results of the comparison study are shown in Table 3 and indicatethat the 15 cell pair electrochemical test device was able to reducehardness as quickly as a 30 cell pair CEDI module under conditions ofequivalent flow rate and volts/cell pair.

TABLE 3 Comparison Study Results Water Electrochemical Property FeedCEDI (control) test device Total 325 ppm/20 gpg 70 ppm/4 gpg 70 ppm/4gpg Hardness Calcium 210 ppm 41 ppm 41 ppm Conductivity 1050 μS/cm 180μS/cm 300 μS/cm Alkalinity 220 ppm Dilution: 40 ppm Dilution: 100 ppm pH7.3 Dilution: 6.9 Dilution: 7.8 Concentrate: 7.4 Concentrate: 7.1 LSI 0Concentrate: 1.2 Concentrate: 0.2

The electrochemical test device yields a product with a conductivity of300 μS/cm, and indicates that the conductivity does not need to bereduced as far as required in the control CEDI device to achieve thesame reduction in hardness. The cleaning rate is thus significantlyimproved and a comparison between the processing times required by bothsystems is illustrated graphically in FIG. 4. As shown, theelectrochemical test device requires at least 25% less time to reducethe hardness of the feed stream than the CEDI control device. Thereduced process time may allow other advantages, including a reductionin the size of the module, a reduction in the module duty cycle, and anincrease in the production rate. Furthermore, the electrochemical testdevice does not use or require cycle switching, as did the CEDI controldevice. A direct comparison between properties of the feed and theproduct water produced by the electrochemical test device is shown belowin Table 4.

TABLE 4 Water Properties of Feed and Product Streams 20 gpg Feed mg/L 4gpg Product Water Property gpg as CaCO₃ gpg mg/L as CaCO₃ TH (gpg asCaCO₃) 19.3 337 4 70 MgH (gpg as CaCO₃) 8.1 139 1.7 29 CaH (gpg asCaCO₃) 11.6 219 2.4 41 HCO/Alkalinity 220 5.8 100 (mg/L as CaCO₃)Sulfate 73 Chloride 106 Na+ 213 TDS (ppm) 550 pH 7.3 7.8 Conductivity(μS/cm) 1023 μS/cm 300 μS/cm

The results from an LSI analysis of the electrochemical test device areshown below in Table 5. The LSI for the concentrate stream of the testdevice is significantly lower than that for the CEDI control device.This is shown in the table below, with the test device consistentlyproducing LSI values at about 0.2 or less.

TABLE 5 LSI Analysis of Electrochemical Test Device Product ConcentrateTime(s) Conductivity Hardness pH Conductivity pH Ca HCO₃ Temp. (C.) LSI0 1050 19 7.25 1050 18.0 0 700 879 15 7.30 2888 6.91 620 480 19 0.111400 680 12 7.39 2456 6.96 530 440 19.4 0.12 2100 521 9 7.59 2190 7.05475 440 20 0.2 2800 392 6 7.86 2058 7.11 450 400 20.2 0.2 3500 300 4 7.9

The ionic conductivity probe used for the study was a Myron L Company™Ultrameter II. The pH was measured by a pH meter available from Oakton™.The alkalinity, calcium content, and total hardness were all measuredusing titration instruments available from Hach™ including model typesAL-AP, EDTA, and HA 71A respectively.

It is to be appreciated that embodiments of the methods and apparatusesdiscussed herein are not limited in application to the details ofconstruction and the arrangement of components set forth in thefollowing description or illustrated in the accompanying drawings. Themethods and apparatuses are capable of implementation in otherembodiments and of being practiced or of being carried out in variousways. Examples of specific implementations are provided herein forillustrative purposes only and are not intended to be limiting. Inparticular, acts, elements and features discussed in connection with anyone or more embodiments are not intended to be excluded from a similarrole in any other embodiment.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. Any references toembodiments or elements or acts of the systems and methods hereinreferred to in the singular may also embrace embodiments including aplurality of these elements, and any references in plural to anyembodiment or element or act herein may also embrace embodimentsincluding only a single element. The use herein of “including,”“comprising,” “having,” “containing,” “involving,” and variationsthereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items. References to “or” maybe construed as inclusive so that any terms described using “or” mayindicate any of a single, more than one, and all of the described terms.Any references to front and back, left and right, top and bottom, upperand lower, and vertical and horizontal are intended for convenience ofdescription, not to limit the present systems and methods or theircomponents to any one positional or spatial orientation.

Having described above several aspects of at least one embodiment, it isto be appreciated various alterations, modifications, and improvementswill readily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be part of thisdisclosure and are intended to be within the scope of the systems andmethods disclosed herein. Accordingly, the foregoing description anddrawings are by way of example only.

What is claimed is:
 1. A water treatment system for a residential orcommercial application comprising: an electrochemical water treatmentdevice comprising a series of alternating cation and anion exchangemembranes positioned between a cathode and an anode; a concentratestream in fluid communication with at least one cation exchange membraneand at least one anion exchange membrane of the series of alternatingcation and anion exchange membranes, the concentrate stream having anLSI that is less than about 1.0; and a dilution stream in fluidcommunication with at least one cation exchange membrane and at leastone anion exchange membrane of the series of alternating cation andanion exchange membranes, wherein the cation and anion exchangemembranes are configured to provide a ratio of a pH of the concentratestream and a pH of the dilution stream to be less than about 1.0, andthe water treatment system is configured to operate such that it doesnot require a reverse polarity cycle.
 2. The water treatment system ofclaim 1, wherein the ratio of the pH of the concentrate stream and thepH of the dilution stream is about 0.9.
 3. The water treatment system ofclaim 1, wherein the pH of the concentrate stream is less than or about7.0.
 4. The water treatment system of claim 1, wherein the LSI of theconcentrate stream is less than or about 0.5.
 5. The water treatmentsystem of claim 1, wherein a conductivity, an alkalinity, and a pH ofthe dilution stream are about 300 μS/cm, about 100 ppm, and greater thanabout 7.0, respectively.
 6. The water treatment system of claim 5,wherein an LSI of the concentrate stream is about 0.2.
 7. The watertreatment system of claim 1, wherein the system does not require aseparate source of acidic water for the concentrate stream.
 8. The watertreatment system of claim 1, wherein the at least one ion exchangemembrane is configured to require at least about 25% less time to reducea hardness of a feed stream to a predetermined level than anelectrochemical device that does not comprise the at least one ionexchange membrane.
 9. A method of treating water for a residential orcommercial application comprising: feeding water from a point of entryto an electrochemical water treatment device comprising a series ofalternating cation and anion exchange membranes positioned between acathode and an anode; and passing the feed water through a concentratingcompartment in fluid communication with a cation and an anion exchangemembrane of the electrochemical water treatment device to produce aconcentrate stream having an LSI that is less than about 1.0; passingthe feed water through a diluting compartment in fluid communicationwith a cation and an anion exchange membrane of the electrochemicalwater treatment device to produce a product stream and a ratio of a pHof the concentrate stream to a pH of the product stream is less thanabout 1.0, and the method does not require a reverse polarity cycle. 10.The method of claim 9, wherein the ratio of the pH of the concentratestream to the pH of the product stream is about 0.9.
 11. The method ofclaim 9, further comprises recirculating the concentrate stream and thepH of the recirculating concentrate stream is less than or about 7.0.12. The method of claim 11, wherein the LSI of the concentrate stream isless than or about 0.5.
 13. The method of claim 9, further comprisingstoring at least a portion of the product stream and measuring aconductivity, an alkalinity, and a pH of the stored portion of theproduct stream.
 14. The method of claim 13, wherein the conductivity,the alkalinity, and the pH of the stored portion of the product streamare about 300 μS/cm, about 100 ppm, and greater than about 7.0,respectively.
 15. The method of claim 14, further comprising calculatingan LSI of the concentrate stream and the LSI of the concentrate streamis about 0.2.
 16. The method of claim 9, wherein the method does notrequire the addition of a separate source of acidic water to theconcentrate stream.